1. Field of the Invention
The present invention relates to an ink jet recording head applicable to a bubble jet printer that utilizes bubbling phenomenon. The invention also relates to an ink jet recording apparatus and an ink jet recording method.
2. Related Background Art
Conventionally, the recording head applicable to the bubble jet recording method is generally provided with fine discharge ports, flow paths, and heat generating elements each installed on a part of each of the flow paths. respectively. The bubble jet recording method is a recording method in which each heat generating element is used to heat liquid locally in each flow path to a high temperature so as to generate each bubble, and then, by utilization of the high pressure exerted at the time of bubbling, liquid is discharged from each of the fine discharge ports to enable liquid to adhere to a recording medium, such as recording paper sheet, for recording.
In order to record the image to be recorded more precisely and colorfully by means of the recording technology of the kind, it is necessary to adopt the related technology and technique so that extremely fine liquid droplets should be discharged in higher density. Here, then, the fundamental importance is that extremely fine flow paths should be formed together with extremely fine heat generating sources. With this in view, making the best use of the simple structure of a bubble jet recording method, the method for manufacturing a head in high density has been disclosed in the specification of Japanese Patent Laid-Open Application No. 8-15629, for example. This disclosed method effectively adopts the technologies of photolithographic process for utilization. Also, there is disclosed in the specification of Japanese Patent Laid-Open Application 62-201254, the heat generating element which provides a larger heating amount on the central portion than the heat amount on each of the end portions thereof in order to adjust the discharge amount of liquid droplets effectively. Usually, the heat generating element uses a resistive member formed by tantalum nitride thin film in a thickness of approximately 0.05 xcexcm. Then, when this film is energized, liquid is bubbled by the application of Joule heat. A resistive heat generating element of the kind is usually provided with a cavitation proof layer formed by metal, such as Ta, in a thickness of approximately 0.2 xcexcm, which is arranged through an insulating member, such as SiN in a thickness of approximately 0.8 xcexcm, in order to prevent the surface of the resistive heating member from being damaged due to cavitation.
Also, in the specification of Japanese Patent Laid-Open Application No. 64-20150, a multiple nozzle ink jet recording head is disclosed, which is characterized in that there are arranged on a plurality of vertical wires and a plurality of intersecting points on a base plate, the rectifying members each allowing the forward current to flow, and each of the heat generating elements connected therewith, respectively. Also, in the specification of Japanese Patent Laid-Open Application 57-36679, there is disclosed a thermal head on which a plurality of diodes are arranged in a array to be able to generate heat by electricity charged in the forward direction.
In general, the ink jet recording head of bubble jet type uses a larger electric current than that of other type in order to generate bubbles for discharging ink. As a result, it is easier for this type of head to generate relatively large noise voltage. However, in the case of the ink jet recording head disclosed in the specification of Japanese Patent Laid-Open Application 64-20150 referred to above, current flows in the forward direction of rectifying element even for the rectifying element and heat generating element which are not driven at that time, there should occur the noise voltage or the like having unstable polarity, such as the voltage lower than the driving voltage of the heat generating element. Consequently, unwanted heating is generated by the heat generating element which is connected with such rectifying element or such heat generating element, hence making it impossible to record high quality images stably in some cases.
Also, many of the conventional ink jet recording heads are produced on condition that heat generating elements, diodes, and logic circuits are produced on a silicon substrate by means of semiconductor process (such as ion injection method). Therefore, an ink jet recording head having a relatively small number of nozzles can be made compact, and there is an advantage that the head can be produced in a simple one process. However, in the case of a multiple head, for example, a length of 12 inches is needed if the multiple head should be produced integrally in order to cover the sheet fully in the widthwise direction, for example. It is made difficult to use any usual silicon wafer, and there is a fear that the manufacturing costs become extremely high.
Under the circumstances, therefore, if the heat generating elements for BJ (bubble jet) recording use are driven in matrix by use of each of the non-linear type elements which is independent of polarity, but capable of providing the MIM type current voltage characteristics that present a higher resistive value at the application of low voltage than the resistive value at the application of high voltage, and which can be manufactured without depending on the conventional semiconductor process, such as ion injection method. There is then a possibility that an elongated ink jet recording head is manufactured with the capability of recording images in high quality stably without generating unwanted heat.
Therefore, the inventors hereof have proposed with the U.S. application Ser. No. 09/586,890 an ink jet recording head provided with the heat generating elements for BJ recording use, which can be driven in matrix using the MIM (Metal Insulator Metal) elements. For this head, the MIM elements, which are non-linear type elements, are provided corresponding to a plurality of heat generating elements for BJ recording use. However, there is a need for dealing with the concentration of electric power of approximately 0.1 GW/m2 or more for the resistive heat generating elements of the heater portion of the recording head for BJ use. Then, the resistive heat generating elements connected in series with the MIM elements should be provided with such electric power, the supply of which has never been experienced for the products having the conventional MIM elements adopted as the non-linear type elements for use of matrix driving. There is then a fear that the efficiency of energy utilization is reduced due to the loss of electric power of the MIM elements themselves when a large electric power should be supplied to the resistive elements arranged in the form of array in high density.
Such loss of electric power of the MIM elements themselves is extremely small for the conventional products that use MIM elements like the liquid crystal or some others, and any serious problem has never been encountered in the art so far. Here, it is considered that this power loss of MIM elements themselves is a problem characteristic of the MIM elements to be used for the BJ recording that should deal with the supply of a large electric power.
Now, therefore, the present invention aims at the provision of an elongated but inexpensive ink jet recording head which is capable of preventing the energy utilization efficiency from being reduced due to the loss of electric power of non-linear type elements themselves. It also aims at the provision of an ink jet recording apparatus, as well as an ink jet recording method.
In order to achieve these objectives, an ink jet recording head of the present invention comprises a resistive heat generating element; and a non-linear type element connected to said resistive heat generating element and having MIM type current voltage characteristics presenting the resistive value thereof being higher at the time of applying lower voltage than the resistive value at the time of applying higher voltage for driving said resistive heat generating elements without depending on polarity. For this ink jet recording head, the resistive heat generating elements and the non-linear type elements are both contributive to the generation of bubbles for discharging ink.
The ink jet recording head of the invention thus structured makes it possible to enable not only the resistive heat generating elements to generate Joule heat when energized, but also, to make the non-linear type elements contributive to bubbling for discharging ink, which are connected with the resistive heat generating elements, respectively, to provide the MIM type current voltage characteristics presenting higher resistive value at the time of low voltage application than the resistive value at the time of high voltage application without depending on polarity. In other words, in addition to heat generated by the resistive heat generating elements for bubbling ink in the ink flow paths, the thermal energy generated by the non-linear type elements, which has been discarded as heat loss conventionally, is utilized for the ink jet recording head to prevent the reduction of its efficiency.
Further, the ink jet recording head of the resent invention may be the one in which each of the resistive heat generating element and each of the non-linear type element connected in series generate bubbles individually almost at the same timing or generate bubbles individually at different timing when electric power is supplied. Also, each of the resistive heat generating element and each of the non-linear type element connected in series may be arranged to generate one bubble when electric power is supplied.
Also, the ink jet recording head of the invention may be arranged to make only the resistive heat generating elements contributive to the generation of bubbles with electric power being supplied to the resistive heat generating element and the non-linear type element. In this case, the discharging amount of ink can be made in a multiple value.
Also, each of the resistive heat generating element and each of the non-linear type element connected in series are arranged substantially in parallel to the ink discharging direction or substantially perpendicular to the ink discharging direction.
Also, a unit having the resistive heat generating element and the non-linear type element connected in series may be arranged on an intersecting point of the matrix circuit formed by the scanning electrodes to input selection potential waveforms being intersected with the information electrodes to input information potential waveforms in accordance with image signals.
Also, the ink jet recording head may be provided with matrix electrodes to structure the matrix circuit for applying voltage to the resistive heat generating element and the non-linear type element connected in series.
Also, the resistive heat generating element and the non-linear type element may be arranged on the intersecting points of the matrix electrodes.
Also, the ink jet recording head of the present invention may be one that discharges ink by generating film boiling in ink with thermal energy generated on the resistive heat generating element and the non-linear type element.
Also, the ink jet recording apparatus of the invention comprises an ink jet recording head provided with a resistive heat generating element; and a non-linear type element connected to said resistive heat generating element in series and having MIM type current voltage characteristics presenting the resistive value thereof being higher at the time of applying lower voltage than the resistive value at the time of applying higher voltage for driving the plurality of resistive heat generating elements without depending on polarity, and carrying means for carrying a recording medium. For the ink jet recording apparatus, the aforesaid ink jet recording head is capable of enabling both the resistive heat generating element and the non-linear type element to be made contributive to the generation of bubbles for discharging ink, being provided with discharge ports to face the resistive heat generating element and the non-linear type element for discharging ink to the surface of a recording medium. Then, this ink jet recording apparatus is provided with a controlling portion for controlling electric power to be supplied to the resistive heat generating element connected in series and the non-linear type element.
The ink jet recording apparatus structured as described above is provided with the ink jet recording head of the present invention, as well as with the controller to control the supply of electric power to the non-linear type elements and the resistive heat generating elements of the ink jet recording head. Therefore, in addition to heat generated by the resistive heat generating elements for bubbling ink in the ink flow paths, the thermal energy generated by the non-linear type elements, which has been discarded as heat loss conventionally, is utilized for the ink jet recording head to prevent the reduction of its efficiency.
Further, for the ink jet recording apparatus of the invention, each of the resistive heat generating elements and each of the non-linear type elements connected in series may be arranged to generate bubbles individually almost at the same timing or at different timing with electric power being supplied for the contribution to the generating bubbles.
Also, for the ink jet recording apparatus of the invention, the controlling portion controls electric power to be supplied to the resistive heat generating element and the non-linear type element connected in series, and may be arranged to control whether both the resistive heat generating elements and the non-linear type elements connected in series, respectively, are made contributive to the generation of bubbles or only the resistive heat generating elements are made contributive to the generation of bubbles. In this case, the amount of ink discharges can be controlled in a multiple value with the execution of the control of the kind.
The ink jet recording method of the present invention is an ink jet recording method which uses the ink jet recording apparatus of the present invention, and comprises the step of recording by discharging ink from the ink jet recording head for the adhesion thereof to the recording surface of the recording medium.
As described above, the ink jet recording method of the invention comprised the step of discharging ink from the discharge ports of the ink jet recording head of the invention so as to record on a recording medium with the adhesion of ink thereon. In other words, in addition to heat generated by the resistive heat generating elements for bubbling ink in the ink flow paths, the thermal energy generated by the non-linear type elements, which has been discarded as heat loss conventionally, is utilized for the ink jet recording head to prevent the reduction of the recording efficiency thereof, hence making it possible to reduce the costs needed for recording.
Further, the ink jet recording method of the invention may be arranged so that with the supply of electric power to the resistive heat generating element connected in series and the non-linear type element, these elements are made contributive to generating bubbles individually almost at the same timing or to generating bubbles individually at different timing.
Also, the ink jet recording method of the invention may be arranged so that with the supply of electric power to the resistive heat generating element and the non-linear type element connected in series, only the resistive heat generating elements are made contributive to generation of bubbles. In this case, with the combination of the recording method in which bubbles are generated individually by the resistive heat generating element and the non-linear type element as described above, it becomes possible to arrange the amount of ink discharge in a multiple value.